1. Field of the Invention
The present invention relates to recording technology using an ink jet recording method, a means for obtaining photographs or graphics, or a hard color copy of computer graphics, color CRT displays, and the like. The present invention is also concerned with ink jet recording technology capable of reproducing color images close to an original image, clearly and at a high density.
2. Description of the Related Art
In ink jet recording methods, ink droplets are formed by various ink discharge methods, and they are adhered to recording members such as paper, converted paper, plastic films, or cloth. This method is silent because the recording head does not contact the member to be recorded, and is advantageous, for example, because high-speed printing is possible, and color images can be easily formed.
Personal computers, from the desk-top type to the lap-top and notebook type, have been increasingly developed to have color display devices. At the present time, when application software utilizing the power of color representation is available, it may be said that making printers having color capability is the most promising field.
The following is required for color ink jet recording:
(1) It should be capable of reproducing a color image close to the original image, clearly and at a high density in the case of photographs, and color graphics, or a hard color copy whose recording density of the recorded image is high, such as computer graphics or color CRT displays, and the like.
(2) There should be no mixing of different colors (bleeding) caused by non-fixing of the ink droplets when different colors are brought close to each other.
(3) The direction in which the ink droplets are discharged for each pulse, and the discharge speed thereof should be constant in order to achieve condition (1).
(4) It is thought that a specific color is used in a very small portion of a recording matter for color recording. Therefore, no defective ink discharge should occur when printing after a lapse of some time from when printing is stopped (including speed variation in (3)) as compared to the conventional monochrome ink.
It has been disclosed in, for example, Japanese Patent Laid-Open No. 1-258979 that the discharge stability during high-frequency driving is improved by having glycerol, methanol, ethanol, isopropyl alcohol, or butanol in the ink.
One way of increasing the recording density of a color image is to decrease the amount of ink discharged in one pulse. However, in an ink jet recording method, in particular, in which ink is discharged by using thermal energy, if conventional ink is used as it is, the direction the ink is discharged and the speed thereof can vary because the air bubbles expand differently for each pulse. Thus, the point at which the ink contacts the recording member varies, and streaks occur in the image. Also, if the amount of ink discharged is decreased as described above, the ink described in Japanese Patent Laid-Open No. 1-258979 is not enough. The same can be said of U.S. Pat. No. 4,931,810.